In anti-aging cosmetics or the like, a skin-tension feeling after application is important as a feeling by which a cosmetic benefit can be promptly realized. Heretofore, there has been much to use a water-soluble polymer such as polyvinyl alcohol to produce a skin-tension feeling, but its effect has not always been satisfied, and therefore, a further improvement for the skin-tension feeling has been required. Furthermore, it is more desirable to provide cosmetics which are excellent in adhesiveness to the skin and have a non-sticky feeling, in addition to the skin-tension feeling effect.
The prior art documents which disclose the arts related to the present invention are as follow.
That is, as shown in Patent Documents 1-3, in order to solve disadvantages of cosmetics such as stickiness and dazzling that result from the incorporation of wax in cosmetics, the applicant of the present invention has proposed a technology in which wax in finely dispersed in a solvent to make a wax emulsion, thereby producing a finely dispersed wax composition that is not only free from the above-mentioned defects but also characterized by high degrees of stability and safety. However, each of the finely dispersed was compositions described in Patent Documents 1-3 is intended to utilize the performance such as lusting and shape-retaining properties of wax itself so that they can be applied to hair cosmetics such as setting lotions and heir mousses and lustering preparations, and none of these patent documents describe or suggest the idea of the present invention, i.e., obtaining the skin-tense feeling after application. In addition, none of these patent documents describe or suggest for obtaining the non-sticky feeling after application and the skin-adhesiveness feeling.
Patent Documents 4-5 also describe hair cosmetic compositions comprising microdispersions of wax; however, the technology disclosed in each of these references is also intended to utilize the performance such as lustering and shape-retaining properties of wax itself so that they can be applied to hair cosmetics such as setting lotions and hair mousses and lustering preparations, and none of these patent documents describe or suggest the idea of the present invention, i.e., obtaining the skin-tense feeling after application. In addition, none of these patent documents describe or suggest for obtaining the non-sticky feeling after application and the skin-adhesiveness feeling.
Patent Document 6 describes the invention related to a wax dispersion whose mean particle size ranges from 0.5 to 100 μm, which comprises a wax phase containing a specified oil component or wax component, and a water phase. However, the particles having such large size are worried about the stability of the dispersion during a long-term storage. In addition, the wax dispersion described in the patent document is used for coating on a base material such as tissue paper for use in production of wet wipe and dry wipe, and there is neither description nor suggestion for incorporating a wax dispersion into an external skin preparation thereby to improve a skin-tense feeling after application. It also does not describe nor suggest with respect to the non-sticky feeling after application and the skin-adhesiveness feeling. Patent Document 6 does not describe regarding the mass ratio of nonionic surfactant to wax; each the ratio of the nonionic surfactant to wax in the wax dispersions shown in Examples (Table 1; [0081]) is less than 1.0.
Patent Document 7 describes the invention related to a pearlescent wax which comprises 30-60 mass % of wax consisting of amorphous and crystalline components, 5-20 mass % of nonionic surfactant and/or amphoteric surfactant, and water if required. That is, the mass ratio of nonionic surfactant to wax in the invention of Patent Document 7 is less than 1.0. Further, Patent Document 7 does not describe nor suggest the step for obtaining a solubilized state of wax under heating in the range of the solubilizing temperature over the melting point of the wax in production of the pearlescent wax, and there is also neither description nor suggestion on dispersion of extremely fine wax particles of 500 nm or less in size. The obtained finely crystallized wax particles in Examples in Patent Document 7 are as large as 12 μm, 13 μm in size (Table 1 in [0077]), and according to the section of Background Art in the patent document, the pearlescent wax is described to have to have particle sizes of generally 5-60 μm ([0002]).
Patent Document 8 describes the invention related to a self-emulsifying base containing an anhydrous wax mixture and an anionic or nonionic emulsifier with an HLB value of at least 10 (claim 8), as well as the use of the above-mentioned anhydrous wax mixture or self-emulsifying base in order to increase the viscosity of an emulsion, particularly oil-in-water type emulsion (claims 13 and 14). In Patent document 8, however, there is neither description nor suggestion on the step for obtaining a solubilized state of wax under heating in the range of the solubilizing temperature over the melting point of the wax in production of the above-mentioned base, and there is also neither description nor suggestion on dispersion of extremely fine wax particles of 500 nm or less in size. In Examples in Patent Document 8, the use of a nonionic surfactant as an emulsifier is described only in the experimental examples shown in Tables 5-7, wherein the mass ratio of “the nonionic surfactant relative to the wax” is less than 1.0 in every experimental example ([0057]-[0059]).
In this connection, it is known that a fluid oil or solid or semisolid wax is compounded as an oil component in an O/W emulsified composition (cream, emulsion, etc.); in such a case, when the compounded ratio of solid or semisolid wax is high, then the stability of the emulsified product becomes worse, and when the ratio of the fluid oil is high, then a skin-tension feeling owing to the solid or semisolid wax becomes difficult to perceive; thus, it is difficult to manage both of stability and feeling in use (skin-tension feeling, non-sticky feeling, etc.).